Google's 'JavaScript killer' marks first birthday with update

Just over a year after it first unveiled the Dart language for large-scale web programming, Google has announced that its purported "JavaScript killer" has hit its first major milestone.

"Today, after plowing through thousands of bug reports and feature requests from the web community, a new, more stable and comprehensive version of Dart is now available and ready to use," wrote Lars Bak, co-developer of the language, in a blog post on Tuesday.

The new release, which Google is calling "M1," is hardly version 1.0. In fact, the Chocolate Factory is referring to it as version 0.1 internally, to indicate that the language and its associated libraries are still likely to undergo significant changes before they reach their finished form.

"M1 is our first release milestone. It's a signal to developers that things are stabilizing, that now's a good time to start building your app in Dart," said Google's JJ Behrens in a video chat on Tuesday. "We're going to try really hard to not make backwards incompatible changes, but rather we're going to be polishing the language, adding to it, and then working a lot on performance."

Much has already changed since Dart's initial public release a year ago. An article on the Dart language website lists 24 significant language changes in the M1 release, not to mention "minor changes and clean-ups."

The Dart team has also been working to improve performance, mostly by enhancing the Dart VM (virtual machine). A new feature called "snapshots" can capture the state of an application right before it starts executing, allowing it to start up as much as ten times faster in subsequent launches. And Behrens says the Dart VM actually now outperforms Google's V8 JavaScript VM on key benchmarks.

Unfortunately, neither improvement will do much to speed up most Dart applications, at least for now. That's because the Dart VM isn't included in any mainstream browser. The primary method for deploying Dart applications today is to compile them to JavaScript – which is one reason why the notion that Dart is a "JavaScript killer" still irks its development team.

"Dart is not out to replace JavaScript," Google's Gilad Bracha insisted during Tuesday's video chat. "This is something that, I guess, various commentators jumped to that conclusion, and once that happens, no amount of denials will help."

Even though most users will run Dart apps as JavaScript, however, the Dart VM can be used to run server-side applications in Node.js fashion, and the Dart SDK ships with a development version of Google's Chrome browser that has the Dart VM built-in, to enable faster debugging. (It has been widely speculated that Google may include a Dart VM in future mainstream Chrome releases, but the search giant has announced nothing officially.)

The M1 release also includes an improved version of the Dart source code editor, which uses static code analysis to enable intelligent refactoring and code completion, as well as introducing a package-management system called Pub, which allows Dart developers to share their packages on Google's servers.

In addition, the new SDK introduces a few new libraries, including an HTML library that works transparently on modern browsers and a library that makes it easier for Dart code to interoperate with code written in JavaScript.

For all the changes introduced in the M1 release, however, there are many more to come. There will definitely be an M2 release before the language approaches its final form, and future updates may even break Dart code written today.

"When we say that the language is stable, you have to take that with a grain of salt, in the sense that we have no intention of making any more breaking changes," Bracha said, before adding, "unless we've really screwed up." ®